Summary Characterization of host immune cell parameters prior to treatment is expected to identify biomarkers predictive of clinical outcome as well as to elucidate why some patients fail to respond to immunotherapy. We monitored blood immune cells from 58 patients with non‐small‐ cell lung cancer (NSCLC) undergoing surgery of the primary tumor and from 50 age‐matched healthy volunteers. Complete leukocyte blood count, the number of circulating dendritic cells (DC), HLA‐DRlow monocytes and several lymphocytic subpopulations were determined by eight‐color flow cytometry. Furthermore, the prognostic value of the immune cell parameters investigated was evaluated by patients’ survival analysis. Compared to the control group, blood of NSCLC patients contained more neutrophils resulting in a higher neutrophil‐to‐lymphocyte ratio (NLR), but a lower number of blood DC, in particular of plasmacytoid DC (pDC), natural killer (NK) cells and naive CD4+ and CD8+ T cells. Furthermore, a higher frequency of CD4+ regulatory T cells (Treg) and HLA‐DRlow monocytes was detected, and smoking had a significant impact on these values. HLA‐DRlow monocytes were positively correlated to the number of neutrophils, monocytes and NLR, but negatively associated with the number of pDC and naive CD4+ T cells. The frequency of Treg, HLA‐DRlow monocytes and naive CD4+ and CD8+ T cells as well as the ratios of CD4/HLA‐DRlow monocytes and HLA‐DRlow monocytes/pDC correlated with patient’s overall survival. Next to Treg, HLA‐DRlow monocytes and naive T cells represent prognostic markers for NSCLC patients and might be useful for monitoring of patients’ responses to immunotherapies in future studies.

Characterization of host immune cell parameters before and during immunotherapy is expected to identify predictive biomarkers for clinical outcome. We prospectively monitored blood immune cells from 35 patients with advanced non–small cell lung cancer undergoing checkpoint inhibitor monotherapy. The aim was to identify parameters correlating with better/worse outcome. Peripheral blood was serially collected before each infusion at the onset and at cycle 3 and 5 of immunotherapy. A complete leukocyte blood count, the lymphocytic subpopulations and the percentages of both HLA-DRlow monocytes and dendritic cells (DC) were monitored. Disease control was defined as partial/complete response and stable disease on computed tomography scan according to RECIST 1.1. The predictive value of the immune cell parameters investigated was evaluated by patients’ survival analysis. Forty percent of patients showed a clinical response, and the global median overall survival was 7.0 months (95% confidence interval: 3.5–10.5). Patients with an initial neutrophil-to-lymphocyte ratio (NLR) ≥5.2, and/or an amount of HLA-DRlow monocytes ≥11% and/or a total DC level ≤0.4% of leukocytes did rarely respond to PD-1 inhibitor therapy. Otherwise, the immunotherapy-induced decrease of the neutrophil-to-lymphocyte ratio and/or HLA-DRlow monocytes and the increase of total DC frequencies were correlated with improved therapy response and prolonged overall survival. Blood values in the third cycle of immunotherapy did already reflect the effects observed. On the basis of the 3 immune cell parameters identified we created 3 different variants of scores that enable to stratify patients into groups of risk/therapy response. Our results warrant further investigation in larger prospective clinical trials for validation.

Although immune checkpoint inhibitor (ICI) therapies have improved the treatment of patients with advanced non-small cell lung cancer (NSCLC), several patients do not achieve durable clinical responses. Biomarkers for the prediction of therapy responses are urgently needed. To identify blood cell parameters correlating with patients’ survival, immune cells from 90 patients with NSCLC undergoing a combination of ICI and chemotherapy were prospectively monitored. At the time point of the first and third antibody administration, complete leukocyte blood count, the percentage of HLA-DRlow monocytes, the percentage of 6-Sulfo LacNAc (slan)+CD16+ non-classical monocytes, and the number of circulating dendritic cell (DC) subtypes, as well as T-, B-, and NK cells were determined by multi-color flow cytometry in peripheral blood. The prognostic value of the immune cell parameters investigated was evaluated by patients’ survival analysis, with progression-free survival (PFS) as the main criterion. A total of 67 patients (74.4%) showed a partial remission or a stable disease, and 35% of patients even survived 12 months and longer. Patients with a neutrophil-to-lymphocyte ratio (NLR) ≥6.1, a frequency of HLA-DRlow monocytes ≥22%, of slan+ non-classical monocytes <0.25% of leukocytes, and/or a sum of myeloid DC (MDC) and plasmacytoid DC (PDC) ≤0.14% of leukocytes had a poorer prognosis. The hazard ratio for PFS was 2.097 (1.208–3.640) for the NLR, 1.964 (1.046–3.688) for HLA-DRlow monocytes, 3.202 (1.712–5.99) for slan+ non-classical monocytes, and 2.596 (1.478–4.56) for the MDC/PDC sum. Patients without any of the four risk factors showed the best PFS. Furthermore, low NK cell counts correlated with shorter PFS (cutoff 200 cells/µL). Female patients had lower baseline NK cell counts and a shorter PFS. Our study confirms the usefulness of blood immune cells as biomarkers for clinical response and survival in NSCLC patients undergoing a combined ICI/chemotherapy.

The aim of this study was to investigate the expression of the coinhibitory molecule PD-L1/CD274 in monocytes and dendritic cells (DC) in the blood of lung cancer patients undergoing PD1 inhibitor therapy and to correlate data with patient’s outcome. PD-L1/CD274 expression of monocytes, CD1c+ myeloid DC (mDC) and CD303+ plasmacytoid DC (pDC) was determined by flow cytometry in peripheral blood at immunotherapy onset. The predictive value of the PD-L1/CD274-expression data was determined by patients’ survival analysis. Patients with a high PD-L1/CD274 expression of monocytes and blood DC subpopulations rarely responded to PD1 inhibitor therapy. Low PD-L1/CD274 expression of monocytes and DC correlated with prolonged progression-free survival (PFS) as well as overall survival (OS). The highest PD-L1/CD274 expression was found in CD14+HLA-DR++CD16+ intermediate monocytes. Whereas the PD-L1/CD274 expression of monocytes and DC showed a strong positive correlation, only the PD-L1/CD274 expression of DC inversely correlated with DC amounts and lymphocyte counts in peripheral blood. Our results implicate that a high PD-L1/CD274 expression of blood monocytes and DC subtypes is a risk factor for therapy response and for the survival of lung cancer patients undergoing PD1 inhibitor therapy.

In this exploratory prospective observational study on 40 small cell lung cancer (SCLC) patients treated with a combination of chemotherapy and immune checkpoint inhibitors, blood immune cells were characterized by multi-color flow cytometry at the baseline and at the third therapy cycle. The numbers of neutrophils and of T-, B-, and NK cells, as well as the frequency of HLA-DRlow monocytes, 6-SulfoLacNAc (slan)+ non-classical monocytes and circulating dendritic cell (DC) subtypes were determined. The prognostic value of the parameters was evaluated by the patient’s survival analysis with overall survival (OS) as the primary endpoint. In addition, blood cell parameters from SCLC patients were compared to those from non-SCLC (NSCLC). The global median OS of patients was 10.4 ± 1.1 months. Disease progression (15% of patients) correlated with a higher baseline neutrophil/lymphocyte ratio (NLR), more HLA-DRlow monocytes, and lower NK cell and DC numbers. The risk factors for poor OS were the presence of brain/liver metastases, a baseline NLR ≥ 6.1, HLA-DRlow monocytes ≥ 21% of monocytes, slan+ non-classical monocytes < 0.12%, and/or CD1c+ myeloid DC < 0.05% of leukocytes. Lymphocytic subpopulations did not correlate with OS. When comparing biomarkers in SCLC versus NSCLC, SCLC had a higher frequency of brain/liver metastases, a higher NLR, the lowest DC frequencies, and lower NK cell numbers. Brain/liver metastases had a substantial impact on the survival of SCLC patients. At the baseline, 45% of SCLC patients, but only 24% of NSCLC patients, had between three and five risk factors. A high basal NLR, a high frequency of HLA-DRlow monocytes, and low levels of slan+ non-classical monocytes were associated with poor survival in all lung cancer histotypes. Thus, the blood immune cell signature might contribute to a better prediction of SCLC patient outcomes and may uncover the pathophysiological peculiarities of this tumor entity.